Molecular mechanics (MM3) calculations on phosphonamidate compounds

Sakakibara, Kazuhisa; Shimazaki, K.; Chen, K.-H; Lii, Jenn‐Huei

doi:10.1016/s0022-2860(00)00645-1

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…Computation of forces from the force field is often an approximation since the force fields are empirical, which means that no accurate form for a force field exists. A diversified range of force field functions exists in literature [72][73][74][75][76][77][78][79]. The total potential energy E pot of a system is the sum contribution due to the bonded E b and non-bonded E nb interactions.…”

Section: Force Fieldsmentioning

confidence: 99%

Computer simulation studies of carbon nanotube and its interactions with water

Venkatesh¹

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Recent discoveries of various forms of nano-materials have stimulated research on their applications in diverse fields. Of particular mention is the carbon nanotubes (CNTs) whose unique mechanical and physical properties has triggered a widespread research interest in a broad range of innovative application in a number of fields such as nanoelectronics, nano-fluidics, biosensors, marine, biological and medical applications. Design of CNT based nano-drug delivery devices have also been a rapidly emerging research in the field of nano-biotechnology. Most of these applications involve interaction of CNTs with water and water based solutions. Much of the underlying physical phenomena such as the effect of water interaction dynamics on the mechanical properties of CNTs remains to be investigated. A thorough knowledge on the influence of water molecule interactions on the mechanical and transport properties of CNTs is useful to determine the lifetime and stability of CNT based nano-fluidics and NEMS devices. In view of this, the major focus of this thesis is to study and understand the mechanical properties of CNTs interacting with water molecules by employing molecular dynamics (MD) simulation. The mechanical properties of single-walled CNTs (SWCNTs) interacting with water molecules have been studied by subjecting the SWCNT to four forms of mechanical loading conditionscompression, tension, torsion and shear. The results indicate that the mechanical performance of SWCNT is strongly affected due to interaction of the surrounding water molecules. In addition, the influence of the SWCNT geometry on the mechanical properties of water submerged SWCNTs is examined. The MD simulations show that SWCNTs with large diameter performs better than SWCNTs with small diameter under mechanical loading. The results also demonstrate that in ABSTRACT ii addition to defect concentration, the location of defects in SWCNT will also affect the mechanical properties of water submerged SWCNT. For the case of capped SWCNTs, it was found that the concentration of water molecule encapsulated inside the SWCNT strongly affects the elastic properties of the SWCNT. Another study involved the transport characteristics of water molecules in CNTs using MD simulation. The transport properties of water molecules in a nano-scale channel such as CNTs is critical for its key role in designing the next generation CNT based nanofluidic devices. The effect of channel diameter, defects and the inter-layer spacing on the transport of water molecules is studied by subjecting the flow of water molecules through CNTs under pressure. The findings show that the efficiency of water transport can be improved by deploying bigger SWCNTs that have wide channel diameter. It was however found that defects in the nano-fluidic system will reduce the transport efficiency of water molecules. The results also show that the inter-layer spacing in a double-walled CNTs (DWCNTs) has a significant influence on the transport efficiency of water molecules. The investigations and conclu...

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Section: Force Fieldsmentioning

confidence: 99%

Computer simulation studies of carbon nanotube and its interactions with water

Venkatesh¹

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Molecular mechanics (MM3) calculations on lithium amide compounds

et al. 2003

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The MM3 force field has been extended to deal with the lithium amide molecules that are widely used as efficient catalysts for stereoselective asymmetric synthesis. The MM3 force field parameters have been determined on the basis of the ab initio MP2/6-31G* and/or DFT (B3LYP/6-31G*, B3-PW91/6-31G*) geometry optimization calculations. To evaluate the electronic interactions specific to the lithium amides derived from the diamine molecules properly, the Lewis bonding potential term for the interaction between the lithium atom and the nonbonded adjacent electronegative atom such as nitrogen was introduced into the MM3 force field. The bond dipoles were evaluated correctly from the electronic charges on the atoms calculated by fitting to the electrostatic potential at points selected. The MM3 results on the molecular structures, conformational energies, and vibrational spectra show good agreement with those from the quantum mechanical calculations.

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Molecular mechanics (MM3) calculations on phosphonamidate compounds

Cited by 2 publications

References 15 publications

Computer simulation studies of carbon nanotube and its interactions with water

Computer simulation studies of carbon nanotube and its interactions with water

Molecular mechanics (MM3) calculations on lithium amide compounds

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